A semiconductor laser diode (LD) using stimulated emission is used as a light source of a recording apparatus or the like. Lighting of high light flux can be obtained by using an LD of high output and a phosphor, and is being developed for realization.
An LD of high output has a problem such that the device deteriorates due to heat generation accompanying absorption of light near a light outgoing end face. There are also problems such that an operation failure due to current injection near an end face and the light emission efficiency deteriorates.
To realize a very reliable LD of high output, there is a method of forming a window structure of low light absorption of a material having a band gap wider than that of an active layer near a light outgoing end face of an active layer. In the case of a nitride semiconductor light emitting device made of a GaN-based material or the like, it cannot be always said that a window structure optimum to realize a very reliable LD of high output is presented.